Field of the Invention
This invention relates to devices by which a medicament in solid finely divided form can be administered to or by patients inhaling through the devices. Such devices are now quite well known for administering medicaments contained in capsules to patients suffering from bronchial conditions such as, for example, bronchial asthma. It is well known for medicament in powder or other finely divided form to be supplied in capsules which are loaded by a patient into such a device. The medicament is then released from the capsule and inhaled by the patient, usually through the mouth, but sometimes through the nose.
The specification of PCT Application Publication No. WO82/01470, GB-A-No. 1387954 and GB-A-No. 2061735 all describe devices for dispensing medicament in finely divided form from capsules. In each of these previously described devices, the capsules are mounted on a rotatable support member on which each capsule in turn can be brought to a position in which it is opened to enable medicament to exit from the capsule to permit it to be inhaled by a patient inhaling through a mouthpiece of the device.
There are disadvantages in the use of capsules, which are made of gelatin, to contain medicaments. Gelatin is relatively unstable and is lacking in physical strength so that the capsules need to be protected by packaging, for example in glass bottles. Environmental degradation of both the capsules and their contents may occur in a relatively short time.
In the device described in UK Patent Specification No. 1387954 the capsules are mounted in what is referred to therein as a blister pack, and is in fact a plurality of capsules mounted in a blister pack on a rotor which is designed to spin during exhalation by the patient to throw medicament out of an opened capsule, whereafter the patient inhales. This has a number of disadvantages, including the fact that the exhalation which is required is more difficult for some patients, for example asthma patients, than inhalation.
In our patent specification GB-A-No. 2129691 we provided a more convenient way of administering medicament to such patients than has been possible hitherto and which avoided the need to pack medicaments in capsules. The device there described makes use of the technique of packaging a medicament by loading the medicament directly into a blister pack comprising a sheet, which may be laminated, of foil or plastics material which acts as a carrier and which is provided with a number of breakable or openable containers called "blisters" incorporating a sheet secured on a first sheet to form a cover or lid. Such blister packs are in common use with tablets of one kind or another, but we have discovered that they can also be used with medicaments in finely divided solid form. GB-A-No. 2129691 provides a device for administering to patients medicaments in blister pack form.
However, the embodiments described in GB-A-No. 2129691 are more bulky than is desirable. It is an object of the present invention to provide a device which avoids or mitigates this problem.
Attention is also directed to our specification GB-A-No. 2142246 which describes various alternative devices for administering medicaments held in solid finely divided form in blister packs.